Article

Previous studies have demonstrated that ankle muscle fatigue alters
postural sway. Our aim was to better understand postural control mechanisms
during upright stance following plantar flexor fatigue. METHOD: Ten healthy young
volunteers, 25.7+/-2.2 years old, were recruited. Foot center-of-pressure (CoP)
displacement data were collected during narrow base upright stance and eyes
closed (i.e. blindfolded) conditions. Subjects were instructed to stand upright
and as still as possible on a force platform under five test conditions: (1)
non-fatigue standing on firm surface; (2) non-fatigue standing on foam; (3) ankle
plantar flexor fatigue, standing on firm surface; (4) ankle plantar flexor
fatigue, standing on foam; and (5) upper limb fatigue, standing on firm surface.
An average of the ten 30-s trials in each of five test conditions was calculated
to assess the mean differences between the trials. Traditional measures of
postural stability and stabilogram-diffusion analysis (SDA) parameters were
analyzed. RESULTS: Traditional center of pressure parameters were affected by
plantar flexor fatigue, especially in the AP direction. For the SDA parameters,
plantar flexor fatigue caused significantly higher short-term diffusion
coefficients, and critical displacement in both mediolateral (ML) and
anteroposterior (AP) directions. Long-term postural sway was different only in
the AP direction. CONCLUSIONS: Localized plantar flexor fatigue caused impairment
to postural control mainly in the Sagittal plane. The findings indicate that
postural corrections, on average, occurred at a higher threshold of sway during
plantar flexor fatigue compared to non-fatigue conditions.
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Langue : ANGLAIS